So far, only the Cribier-Edwards valve has been deployed via all three techniques. The CoreValve has been deployed only via the retrograde technique. The Edwards SAPIEN valve has been deployed with retrograde and transapical approaches (see www.edwards.com/Products/TranscatheterValves/SapienTHV.htm and www.corevalve.com for animations depicting these techniques).
EXPERIENCE WITH THE CRIBIER-EDWARDS VALVE
The Cribier-Edwards valve has three leaflets made from equine pericardial tissue sutured inside a balloon-expandable stainless steel 14-mm stent ( Table 1 ).11,23,33 With the use of a specially designed mechanical crimping device, the aortic valve prosthesis is mounted over a 3-cm-long balloon catheter, expandable to a diameter of 22 to 26 mm (NuMed Inc, Hopkinton, NY). 11,23,30,33
After this prosthesis was tested in animal models, 14,15 a trial for compassionate use in humans was begun, called the Initial Registry of Endovascular Implantation of Valves in Europe (I-REVIVE) trial. This trial was later continued as the Registry of Endovascular Critical Aortic Stenosis Treatment (RECAST) trial. 23 All patients were formally evaluated by two cardio-thoracic surgeons and were deemed inappropriate for surgical aortic valve replacement. 23
The success rate with the antegrade percutaneous approach was 85% (23 of 27 patients) and 57% for the retrograde approach (4 of 7 patients). 11,23,30–33 Procedural limitations were migration or embolization of the prosthetic valve, failure to cross the stenotic aortic valve, and paravalvular aortic regurgitation. 23 Anatomic and functional success was evidenced by improvement in aortic valve area, increase in left ventricular ejection fraction, and improved New York Heart Association functional class, all of which were sustained at up to 24 months. 23
Webb et al 11 reported similar results with retrograde implantation of the Cribier-Edwards valve in a cohort of 50 patients. 11 The main difference between the two studies was the expected occurrence of aortofemoral complications with the retrograde approach. 11,26 Procedural success increased from 76% in the first 25 patients to 96% in the second 25, and the 30-day mortality rate fell from 16% to 8%, which reflected the learning curve. Importantly, no patients needed conversion to open surgery during the first 30 days, and at a median follow-up of 359 days 35 (81%) of 43 patients who underwent successful transcatheter aortic valve replacement were still alive. 11 Additionally, significant improvement was noted in left ventricular ejection fraction, mitral regurgitation, and New York Heart Association functional class, and these improvements persisted at 1 year. 11
Lichtenstein et al 31 and Walther et al 32 successfully implanted the Cribier-Edwards valve using the transapical approach in a very high-risk elderly population with poor functional class. All patients were deemed unsuitable for standard surgical valve replacement and also for percutaneous transfemoral aortic valve implantation because of severe aorto-iliac disease. In both studies, the short-term and mid-term results were encouraging.
These experiences with the Cribier-Edwards valve showed that device- and technique-related shortcomings could be addressed. To date, more than 500 percutaneous aortic valve replacement procedures have been done with the Cribier-Edwards valve worldwide, with a greater than 95% technical success rate in the latest cohorts. 36 Importantly, use of a larger (26-mm) prosthetic valve has been associated with a lower rate of prosthetic valve migration or embolization, and with a significantly lower rate of paravalvular aortic regurgitation. 11,23